Inhibition of TSH subunit glycosylation by tunicamycin leads to rapid intracellular proteolysis of nonglycosylated subunits. Neither nonglycosylated nor core-glycosylated alpha combines with normal TSH-beta in cell-free combination experiments. Subcellular fractionation studies show a translational block of nascent chains at 11,000 daltons, presumably caused by glycosylation. Subunit processing occurs in both the rough and smooth endoplasmic reticulum while combination occurs in the smooth endoplasmic reticulum or golgi.